This invention relates generally to an electromagnetic coupling such as a clutch or brake and, more particularly, to an armature assembly for such a coupling.
Booth et al., U.S. Pat. No. 5,036,964 and Booth, U.S. Pat. No. 5,150,779 each disclose an electromagnetic clutch in which an armature is connected to a driven hub on a rotatable shaft and is adapted to be frictionally coupled to a driving rotor when an electromagnet is energized to engage the clutch. When the clutch is engaged, the rotor acts through the armature to rotate the driven hub and the shaft.
The armature assembly disclosed in each of the aforementioned patents includes a resilient plastic spider with a web which acts to connect a low magnetic reluctance armature plate for rotation with the driven hub. The web flexes axially in order to permit the armature plate to move toward and away from the rotor when the clutch is engaged and disengaged. The hub is insert molded in place when the spider is molded and thus the plastic of the spider is bonded to and encapsulates part of the hub in order to join the hub to the spider.
Clutches are used with different types of shafts which require different types of armature hubs. As a result, it has been necessary in the past to customize various armature assemblies having different types of hubs molded in place in the spider. A substantial tooling investment is required to achieve this and, in addition, several different types of customized armature assemblies must be maintained in inventory.